--- a/slides/slides05.tex	Wed Oct 23 07:28:23 2013 +0100
+++ b/slides/slides05.tex	Fri Oct 25 14:13:27 2013 +0100
@@ -576,11 +576,12 @@
 \begin{itemize}
 \item The star-case in our proof about the matcher needs the following lemma
 \begin{center}
-\bl{$Der\,c\,A^* = (Der c A)\,@\, A^*$}
+\bl{$Der\,c\,A^* = (Der\,c\,A)\,@\, A^*$}
 \end{center}
 \end{itemize}\bigskip\bigskip
 
 \begin{itemize}
+\item \bl{$A^* = \{""\} \cup A\,@\,A^*$}
 \item If \bl{\texttt{""} $\in A$}, then\\ \bl{$Der\,c\,(A @ B) = (Der\,c\,A) @ B \cup (Der\,c\,B)$}\medskip
 \item If \bl{\texttt{""} $\not\in A$}, then\\ \bl{$Der\,c\,(A @ B) = (Der\,c\,A) @ B$}